code: def test_inverse_transform_when_encode_unseen():
      df1 = pd.DataFrame(
          {"words": ["dog", "dog", "cat", "cat", "cat", "bird"]}
      )
      df2 = pd.DataFrame(
          {"words": ["dog", "dog", "cat", "cat", "cat", "frog"]}
      )
      df3 = pd.DataFrame(
          {"words": ["dog", "dog", "cat", "cat", "cat", np.nan]}
      )
      enc = OrdinalEncoder(encoding_method="arbitrary", unseen="encode")
      enc.fit(df1)
      dft = enc.transform(df2)
      pd.testing.assert_frame_equal(enc.inverse_transform(dft), df3)
  
file_path: feature_engine/tests/test_encoding/test_ordinal_encoder.py
imports: import numpy
  import pandas
  import pytest
  from feature_engine.encoding import OrdinalEncoder
label_desc: Use image node_id 14 for calling a global function with example usage: test_inverse_transform_when_encode_unseen() without return types